JP2007127606A - Device and method for measuring complex permittivity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the complex permittivity of such a dielectric substance as to be used in a thin-film state, in a film state, or in a small-diameter wire state, which has been hard to use as a measurement specimen up to now. <P>SOLUTION: An (N+1)layer round rod body is made of a substance of an axisymmetric structure comprising a specimen layer of unknown complex permittivity and N layers (air gaps can be included therein) of known complex permittivity. The rod body is put through and fixed in a wave guide tube with through holes provided in its confronting side walls. A propagation characteristic parameter is measured on the guide tube with the rod body put therethrough and fixed therein. The unknown complex permittivity of the specimen layer is derived by applying measurement results on the characteristic parameter to a theoretical expression of the characteristic parameter which is a function of the unknown complex permittivity and theoretically determined by the shapes of the guide tube and of the rod body and by the known complex permittivity of the N layers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a complex dielectric constant measuring apparatus and method for measuring a complex dielectric constant of a dielectric, for example, a general dielectric material used for a printed wiring board or the like, or a complex dielectric of a functional dielectric material such as a micro wave absorber for an electronic component. It can be applied to rate measurement.

  Conventionally, there are the following methods for measuring the dielectric constant (complex dielectric constant) of a dielectric.

  First, there is a resonator method that calculates from a change in resonance frequency and Q value when a sample is inserted into the resonator (see, for example, Patent Document 1).

  Second, there is a method of filling a sample in a coaxial waveguide or a rectangular waveguide and calculating a complex dielectric constant from the amplitude and phase change of only the reflected wave (see, for example, Patent Document 2 and Patent Document 3). .

  Third, there is a coaxial probe method that is widely used as a method for easily measuring liquid materials and the like. The coaxial probe method is a method in which the surface from which the coaxial tube is cut is closely attached to a sample for measurement.

Fourth, there is a free space method in which a sample having a large (about 200 mm × 200 mm) surface is irradiated with a plane wave on the surface to measure reflection and transmission coefficients and calculate a complex dielectric constant.
Japanese Patent Laid-Open No. 08-122375 Japanese Patent Laid-Open No. 11-118732 Japanese Patent Laid-Open No. 11-166951

  The four types of measurement methods described above are solid functions such as those used in thin film states, film states, and small-diameter wire states, such as general-purpose insulating materials used for printed wiring boards and the like, and micro wave absorbers for electronic components. The measurement of the complex dielectric constant of the conductive dielectric material has a problem.

  In the case of the first resonator method, the complex permittivity can be obtained only from the characteristic at one resonance frequency, and there is a fear that the measurement accuracy is low. Moreover, in order not to disturb resonance, it is necessary to manufacture a smaller sample for a sample with a larger loss, and there is a problem that sample preparation is difficult.

  In the method using the second waveguide, it is necessary to process the sample shape so as to match the cavity shape of the waveguide. In addition, a material used in a thin film state or a film state is measured by a sample having a considerable volume, and the difference in shape between the use state and the measurement state is large.

  The measurement range of the dielectric constant by the third coaxial probe method is practically a range that can be measured using radio waves up to about 20 MHz, and is considerably limited. In addition, in the case of a thin sample (10 mm or less), the influence on the back side of the measurement surface becomes large, so that it is not suitable for a film sample. In addition, since the measurement data of ion-exchanged water is calibrated as known, it is a relative measurement including an error factor.

  The fourth free space method needs to produce a sample with a large area and no distortion, and is difficult to use except for measurement of a radio wave absorber for a road or a dark room.

  Therefore, there is a need for a complex permittivity measuring apparatus and method suitable for measuring the complex permittivity of a dielectric that is difficult to be a measurement sample in the past, such as used in a thin film state, a film state, or a small diameter line state.

  In order to solve such a problem, a complex dielectric constant measuring apparatus according to the first aspect of the present invention includes a sample layer having an unknown complex dielectric constant and an N layer having an unknown complex dielectric constant (which may include an air gap layer). A circular rod made of a material having an axially symmetric structure, a waveguide having through holes provided in opposing side walls for passing through the circular rod of the (N + 1) layer, and the through holes Measuring means for measuring a propagation characteristic parameter of the waveguide through which the circular rod is fixed through, a shape of the waveguide and the circular rod, and a known complex dielectric constant of the N layer Analyzing means for deriving the complex dielectric constant of the unknown sample layer by applying the measurement result of the measuring means to the theoretical expression of the propagation characteristic parameter that is theoretically determined from It is characterized by including.

  Further, the complex dielectric constant measuring method of the second aspect of the present invention has an axially symmetric structure of a sample layer whose complex dielectric constant is unknown and an N layer whose complex dielectric constant is known (which may include an air gap layer). A (N + 1) layer circular rod made of a material is fixedly penetrated into a waveguide having through holes in opposing side walls, and the circular rod is propagated through the waveguide. A theory of propagation characteristic parameters as a function of an unknown complex dielectric constant, which is determined theoretically from the shape of the waveguide and the circular rod and the known complex dielectric constant of the N layer. The characteristic is that the complex dielectric constant of an unknown sample layer is derived by applying the measurement result of the propagation characteristic parameter to the equation.

  According to the present invention, one layer of (N + 1) layers of circular rods penetrating the waveguide can be used as a sample layer, so that it is conventionally used in a thin film state, a film state, a small diameter line state, or the like. Then, it is possible to measure the complex dielectric constant of a dielectric that is difficult to be a measurement sample.

(A) First Embodiment Hereinafter, a first embodiment of a complex permittivity measuring apparatus and method according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram showing a schematic overall configuration of a complex dielectric constant measuring apparatus 10 of the first embodiment.

  In FIG. 1, the complex permittivity measuring apparatus 10 of the first embodiment includes a perforated rectangular waveguide 11, a sample 12, a sample supporting circular rod 13, a network analyzer 14, a computer 15, a constant temperature and humidity chamber 16, and the like. have.

  As shown in FIG. 2, the perforated rectangular waveguide 11 has a circular transparent shape through which the sample-supporting circular rod body 13 penetrates at the center of two wider side walls (wide walls) of the four side walls. It has a hole 11a. As will be described later, the S-parameter is measured by sweeping the traveling wave inside the perforated rectangular waveguide 11, but depending on the frequency sweep range, a plurality of perforated rectangular waveguides that can correspond to different frequency bands. 11 is prepared and used by exchanging. As the perforated rectangular waveguide 11, for example, a standardized shape (for example, IEC standard) can be applied when it is assumed that there is no through hole 11a. Here, the diameter of the through hole 11a may be different for different types of waveguides, or may be the same.

  The sample 12 is a solid or non-fluid body to be measured for the complex dielectric constant (which may be solid or non-fluid at the time of measurement), and is supported by the sample support circular rod 13 as described later. is there. The sample-supporting circular rod 13 has a sufficient length that can penetrate the perforated rectangular waveguide 11, and may be either cylindrical or cylindrical. Note that the sample 12 may be a fluid as long as it is in a state of being handled in the same manner as a solid material. For example, a non-flowing fluid filled in a cylindrical sealed container whose upper and lower portions are closed or an open container (sample support circular rod 13) in which only the cylindrical upper end is opened is Sample 12 can be obtained.

  The sample 12 may be provided as a thin film on the outer peripheral surface or the inner peripheral surface of the sample support circular bar 13. Here, as a method for forming the thin film of the sample 12, any of the existing methods for forming a thin film may be applied. For example, a method such as vapor deposition, coating, or printing may be used. Further, when the sample 12 is in the form of a film or cloth, the sample 12 is provided by being wound around the outer peripheral surface of the sample support circular bar 13. The number of turns at this time is not questioned. In addition, when the sample 12 is in the form of a film or cloth, the sample 12 in the form of a scroll may be inserted into the cylindrical sample support circular bar 13. Further, the sample 12 may be formed as a small-diameter columnar rod and inserted into the cylindrical sample support circular rod 13. At this time, the sample 12 is fitted to the sample support circular rod 13. For example, as shown in the cross-sectional view of FIG. 3A, there may be an air layer 17 between the sample 12 and the sample support circular rod 13 (in this case, for example, The sample 12 is connected at the upper and lower ends of the sample support circular bar 13). Moreover, the sample support circular rod 13 is not limited to one, and may be composed of two or more members. For example, as shown in the cross-sectional view of FIG. 3B, a thin film of the sample 12 is formed on the outer peripheral surface of the cylindrical first sample support circular bar 13a, and the first sample support circle having the sample 12 is formed. The cylindrical sample body 13a may have a cylindrical second sample support circular bar body 13b so as to concentrically cover the bar body 13a in contact or via the air layer 17.

  The sample 12, the sample support circular rod 13 (including a plurality of cases), and the air layer 17 are concentric with respect to the central axis that connects the centers of the upper and lower through holes 11 a of the perforated rectangular waveguide 11. In other words, they are arranged axisymmetrically.

  When the sample 12 is in the form of a film or cloth, the sample 12 is made into a cylindrical or columnar shape by winding, and when it is other than a film or cloth, it can be formed or cut out. The sample 12 may be cylindrical or columnar, and may pass through the through hole 11a of the perforated rectangular waveguide 11 without using the sample support circular rod 13. However, it is necessary to have an axisymmetrical layer having a complex dielectric constant (sample 12) and a layer having a known complex dielectric constant (including an air gap layer). The layer having a known complex permittivity may be a layer that is known when the complex permittivity of the sample 12 is obtained, and a layer that obtains the complex permittivity before the complex permittivity of the sample 12 by a series of measurement procedures. There may be.

  Here, in the case of an arrangement mode in which the whole or a part of the sample-supporting circular rod 13 is arranged around the outside of the sample 12, the electromagnetic field energy of the waveguide 11 is used as an outer layer of the sample 12. It is preferable to provide a lens-like function by providing a layer having a complex dielectric constant that concentrates at or near the axis that is the target of the axis. In this case, it is preferable that the innermost layer of the axially symmetric layers is a layer formed of a solid substance in a cylindrical shape because the degree of lens function is high.

  The network analyzer 14 is a general two-port vector network analyzer. In the case of the first embodiment, the network analyzer 14 measures an S parameter as a complex number as a propagation characteristic parameter. The network analyzer 14 is connected to the perforated rectangular waveguide 11 through a coaxial waveguide converter. The network analyzer 14 measures the S parameter at each frequency while sweeping the frequency.

  The computer 15 is a computer such as a personal computer provided with input / output devices such as a display and a keyboard, and various storage devices, and calculates the complex dielectric constant of the sample 12 from the S parameter obtained by the network analyzer 14. Is. The processing method by the computer 15 will be described in detail in the description of the measurement procedure described later.

  The constant temperature and humidity chamber 16 accommodates the perforated rectangular waveguide 11 inside regardless of whether the sample 12 or the sample support circular rod 13 is attached, and the temperature and humidity around the perforated rectangular waveguide 11. Is set to the set value. In general, the complex dielectric constant is highly dependent on temperature. Some materials (the sample 12 and the sample-supporting circular rod 13) easily absorb water, which may have a large influence on the complex dielectric constant. Therefore, by installing a rectangular waveguide 11 with a hole in the constant temperature and humidity chamber 16 for measurement, the reproducibility of the experiment is improved, and the temperature characteristics of the complex dielectric constant can be measured.

(A-2) Operation of the First Embodiment Next, the measurement operation of the complex permittivity measuring apparatus 10 of the first embodiment (the complex permittivity measuring method of the first embodiment) will be described with reference to the drawings. explain.

  FIG. 4 is a flowchart showing the flow of the procedure for measuring the complex dielectric constant of the sample 12.

  In the measurement, the shape information of the waveguide 11 to be used (for example, the long side, the short side, the length of the cavity, the diameter of the through hole 11a, etc.), the sample 12 and the sample support circle are used. Information on each layer of the (N + 1) layer composed of the rod-like rod 13 or the like is input (S1). Enter the radius for the center layer of the axis target, and the layer thickness for the other layers. Further, a complex dielectric constant is input for each of the other N layers except for one layer of the sample 12.

  In addition, a storage table in which the type of the waveguide 11 and the shape information of the type of the waveguide are associated in advance is prepared, the type information of the waveguide 11 is input, and the type of the waveguide The shape information may be read from the storage table. If the type of the sample support circular rod 13 to be used is limited, similarly, an information storage table is prepared and the type information of the sample support circular rod 13 is input. Alternatively, the information on the N layer related to the sample support circular rod 13 may be read, and only the information on one layer related to the sample 12 may be input. The theoretical function described later affects not only the complex permittivity of each layer but also the complex permeability of each layer, but since the error is acceptable, the complex permeability of all layers may be regarded as “1”. The complex magnetic permeability for the layer with the unknown dielectric constant (the layer of the sample 12) is regarded as “1”, and the complex magnetic permeability may be input for the layer with the known complex dielectric constant.

  Next, calibration is performed by a TRL (Through-Reflection-Line) calibration function of the network analyzer 14 (S2). In order to determine the reference plane of the 2-port S parameter of the measurement system, for example, TRL (Through-Reflection-Line) calibration is performed using both sides of the waveguide 11 as reference planes, and then the phase of the waveguide 11 is corrected by phase correction. The reference plane is moved to a cross section including a central axis connecting the centers of the upper and lower through holes 11a.

  After that, measurement of S-parameters for the perforated rectangular waveguide 11 in which the sample support circular rod 13 is not mounted, the layer of the sample 12 is not provided (or the layer of the sample 12 is replaced with an air layer) ) Measurement of S-parameters for the perforated rectangular waveguide 11 equipped with the sample supporting circular rod 13 and the perforated rectangular waveguide equipped with the sample supporting circular rod 13 provided with the layer of the sample 12 The measurement of the S parameter for the tube 11 is sequentially performed using the network analyzer 14, and the measured S parameter is input to the computer 15 (S3 to S5). The S parameter is measured by sweeping the frequency. Depending on the frequency sweep range, a plurality of perforated rectangular waveguides 11 that can correspond to different frequency bands are used interchangeably.

  Measurement of S-parameters for the perforated rectangular waveguide 11 without the sample-supporting circular rod 13 and the layer of the sample 12 is not provided (or the layer of the sample 12 is replaced with an air layer) Only one of the measurement of the S parameter for the perforated rectangular waveguide 11 to which the sample support circular rod 13 is attached may be performed.

Here, let us consider a state in which a sample-supporting circular rod 13 provided with a layer of the sample 12 passes through the rectangular waveguide 11 with holes. It is assumed that the sample 12 and the sample-supporting circular rod body 13 are composed of N + 1 layers (an air gap layer may be included), and the complex dielectric constant of each layer is denoted by ε ₁ to ε _{N + 1} , respectively.

The four S parameters s11, s12, s13, and s14 for the perforated rectangular waveguide 11 through which the sample support circular rod 13 provided with the layer of the sample 12 passes are the traveling waves of the perforated rectangular waveguide 11. Is theoretically expressed by a parameter that defines the shape of the perforated rectangular waveguide 11 and a plane wave scattering coefficient on the sample-supporting circular rod 13 provided with the layer of the sample 12. In addition, the plane wave scattering coefficient of the sample-supporting circular rod 13 provided with the layer of the sample 12 is theoretically determined by the complex symmetry of each layer as a function of ε ₁ to ε _{N + 1} due to its axial symmetry. Can be expressed as

As a result, the function G (s11, s12, s13, s14) including only the four S parameters s11, s12, s13, s14 (for example, a simple average of four parameters) complex dielectric constant ε ₁ ~ε _{N + 1} of the function F _{(ε 1, ..., ε X} , ..., ε N + 1) is expressed as. The complex dielectric constant ε _X is a complex dielectric constant of the sample 12, and X is any one of 1 to N + 1.

F (ε ₁ ,..., Ε _X ,..., Ε _{N + 1} ) = G (s11, s12, s13, s14) (1)
Here, G (s11, s12, s13, s14) on the right side in equation (1) can be set to a specific value by applying the measured values of the four S parameters s11, s12, s13, s14. . Note that measurement of the same target may be performed a plurality of times, and four S parameters s11, s12, s13, and s14 each averaged may be applied. On the other hand, among the N + 1 complex dielectric constants related to the function F (ε ₁ ,..., Ε _X ,..., Ε _{N + 1} ) on the left side in the equation (1), the unknown complex dielectric constant ε _X is the complex dielectric constant of the sample 12. Since only the rate, the function F (ε ₁ ,..., Ε _X ,..., Ε _{N + 1} ) is a function for the unknown complex dielectric constant ε _X.

Therefore, the measured S parameters s11, s12, s13, s14, other complex dielectric constants ε _{1 to} ε _{N + 1} (excluding ε _X ) input as known information, the perforated rectangular waveguide 11, etc. The complex permittivity ε _X of the sample 12 can be obtained by solving the equation (1) according to the shape information. For solving the equation (1), for example, an approximate value search algorithm such as Newton's method can be used. The right side of the equation (1) becomes a certain value by a calculation process using the measured value. Set a certain value as the unknown complex dielectric constant ε _X , calculate the left side of equation (1), calculate the difference from the right side, and change the set value of the unknown complex dielectric constant ε _X according to the difference Then, the left side of the equation (1) is recalculated, the difference from the right side is calculated and evaluated, and in the same manner, the unknown complex permittivity ε _X is set so that the difference from the right side falls within an allowable error range. Explore.

Equation (1) described above uses only the S-parameter measurement results for the perforated rectangular waveguide 11 on which the sample-supporting circular rod 13 provided with the layer of the sample 12 is mounted, and the complex dielectric of the sample 12 is used. This is an expression applied when the rate ε _X is obtained.

Further, the complex dielectric constant ε _X of the sample 12 can be obtained by applying a differential function E (ε _X ) as shown in the equation (2).

E (ε _X ) = F (ε _X ) −F ^ (ε _X )
= G (s11A, s12A, s13A, s14A)
-G (s11B, s12B, s13B, s14B) (2)
In the equation (2), the function F (ε _X ) is the same as the left side in the equation (1), and the function F ^ (ε _X ) is measured without including the unknown complex dielectric constant ε _X. This is a theoretical function similar to the left side of the equation (1) in the environment. In other words, the former F (ε _X ) is a theoretical function for the perforated rectangular waveguide 11 on which the sample-supporting circular rod 13 provided with the sample 12 layer is mounted. Accordingly, the theoretical difference function E (ε _X ) is also the only unknown parameter of the complex permittivity ε _X of the sample 12.

As a case where a theoretical function F ^ (ε _X ) that does not include an unknown complex dielectric constant ε _X can be applied, a perforated rectangular waveguide 11 equipped with a sample-supporting circular rod 13 on which a sample 12 is not provided. A measurement environment for a perforated rectangular waveguide 11 equipped with a sample support circular rod 13 in which a portion of the sample 12 is replaced with a layer having a known complex dielectric constant (for example, an air gap layer), Measurement environment for a perforated rectangular waveguide 11 not mounted with a sample support circular rod 13 (assuming that a non-existing sample support circular rod 13 consisting of only one air gap layer is mounted) Can be mentioned.

The function value G (s11A, s12A, s13A, s14A) is a value obtained from the measurement result of the perforated rectangular waveguide 11 on which the sample support circular rod 13 provided with the layer of the sample 12 is mounted. The function value G (s11B, s12B, s13B, s14B) is a value obtained from the measurement result in the measurement environment in which the theoretical function F ^ (ε _X ) not including the complex dielectric constant ε _X is applied. .

Therefore, the complex dielectric constant ε _X of the sample 12 can also be obtained by solving the equation (2). For solving the equation (2), for example, an approximate value search algorithm such as Newton's method can be used. When applying equation (2), even if an offset or the like enters during measurement (for example, even if there is an error that cannot be removed by TRL calibration), it is canceled by the difference processing, and the calculation accuracy is calculated from equation (1). Can be expected to improve.

As described above, the complex dielectric constant ε _X of the sample 12 is obtained using the measurement results of the S parameters for the different measurement environments measured in steps S3 to S5 (S6).

FIGS. 5A1 and 5A2 are graphs showing examples of measured values s _ij (ij is any one of 11, 12, 21, and 22) of the S parameter of the perforated rectangular waveguide 11 only. FIGS. 5B1 and 5B2 are graphs showing an example of S parameter measurement values s _ij for the perforated rectangular waveguide 11 to which a certain sample support circular rod body 13 is attached. It can be seen that the S-parameters change as the body 13 is attached.

The computer 15 describes or calculates a function F (ε ₁ ,..., Ε _X ,..., Ε _{N + 1} ), a function G (s 11, s 12, s ₁₃ , s ₁₄ ), a function E (ε _X ), and the like. A routine is provided. Then, according to the input shape information of the waveguide 11 to be used and the layer information of the sample support circular rod 13, the unknown is set to only the complex dielectric constant ε _X of the sample 12 by parameter setting processing for the routine. By applying the value of the S parameter given from the network analyzer 14 and solving the above equation (1) or (2) (the solution routine is also mounted in the computer 15), the complex dielectric of the sample 12 is obtained. The rate ε _X is obtained.

Since the S parameter at each frequency is obtained using the frequency sweep function of the network analyzer 14, the complex permittivity ε _X of the sample 12 is obtained for each frequency based on the S parameter at each frequency. As the complex dielectric constant ε _X of the sample 12, an average value of measured values for each frequency can be applied.

Before obtaining the complex dielectric constant ε _X of the sample 12, the complex dielectric constant of a known layer is obtained, and information on the difference between the complex dielectric constant obtained by measurement of the known layer and the known value is obtained to obtain a network. It may be used for calibration of the analyzer 14.

  FIG. 6A shows the measurement result of the complex relative permittivity when the sample 12 is an acetal homopolymer rod (indicated by POM; there is no sample support circular rod 13), and the sample 12 also has a sample support circle. The measurement result of the complex dielectric constant in the case of air (noted with Air) to which the rod 13 is not attached is also shown. Note that in FIG. 6B, the measurement result of the dielectric loss tangent is also shown for reference. When the measurement object is air, it can be seen that the relative permittivity is 1, the loss is as close to 0 as possible, and the measurement error level is reached.

  As is clear from the explanation using the above-described formula (1) or (2), the sample 12 is placed between the centers of the upper and lower through holes 11a together with the support and the like (including the case where there is no support). If they are arranged concentrically with respect to the connecting central axis, the complex relative dielectric constant of the unknown sample 12 can be obtained.

  For example, when the number of concentric layers corresponds to N + 1 and only one of the layers (or the center layer) has an unknown complex dielectric constant, a processing routine for expressing equation (1) or (2) 15 and correspond to concentric layers up to N + 1 layers (which may include an air gap layer) including one unknown layer. Then, from the function G expressed by the S parameter measured using the network analyzer 14 and the function F or E obtained so as to include the complex dielectric constant that is analytically unknown from the geometrical axis symmetry, It is only necessary to form an equation as described by using the equations (1) and (2) as an example and solve it by the Newton method or the like to obtain the complex dielectric constant of the unknown layer.

  In addition, when calculating | requiring the temperature characteristic, humidity characteristic, etc. of the complex dielectric constant of the sample 12, what is necessary is just to switch the setting temperature and setting humidity in the constant temperature and humidity chamber 16, and to repeat the above-mentioned measurement.

(A-3) Effect of First Embodiment As described above, according to the first embodiment, concentric circles are formed with respect to the central axis that connects the centers of the upper and lower through holes 11a of the perforated rectangular waveguide 11. The complex dielectric constant can be obtained when the complex dielectric constant of only one layer (sample) is unknown among the N + 1 concentric layers arranged in a shape and penetrating the perforated rectangular waveguide 11. .

  Therefore, it is possible to measure a complex dielectric constant of a dielectric used in a thin film state, a film state, a small diameter line state, or the like.

  Since the sample has a simple structure such as a cylinder or a cylinder, the workability is good and it can be applied to almost all materials of a solid sample. In addition, film-like (for example, flexible printed circuit board materials), cloth-like or non-woven-like specimens, etc., are wound around a known base with a cylindrical complex dielectric constant or become cylindrical around the hole of the waveguide. It can measure by arranging. Furthermore, paints, thin film materials, surface treatment layers, etc. can also be applied to the outer peripheral surface of a base having a known cylindrical complex dielectric constant by applying a uniform dielectric constant, forming a thin film, or surface treating the complex dielectric constant. Can be measured. In addition to the method of positioning the linear material on the central axis of the concentric circle, the complex dielectric constant is also measured by winding it around the entire outer periphery of the sample-supporting circular rod 13 (for example, winding like a coil spring). can do.

  In the first embodiment, the frequency used for the measurement is not limited to the resonance frequency, and can be measured at each frequency within the sweep range. Therefore, the frequency characteristic of the complex dielectric constant can be obtained. In addition, in the case of a sample having no frequency dependence, it is expected that a highly accurate measurement value can be obtained by calculating a representative value (for example, an average value) from the measurement result at each frequency.

  Here, by diversifying the types of the waveguide 11, it is possible to measure the complex dielectric constant within a range from several hundred MHz to about 70 GHz.

  Furthermore, according to the first embodiment, since the waveguide for measurement is arranged in the constant temperature and humidity chamber 16, the temperature and humidity characteristics of the complex dielectric constant can be obtained.

(B) Second Embodiment Next, a second embodiment in which the complex dielectric constant measuring apparatus and method according to the present invention is applied when the sample 12 is a liquid crystal will be briefly described.

  FIG. 7 is a perspective view showing components such as the sample 12 and the sample support circular bar 13 in the second embodiment.

  In the case of the second embodiment, the sample 12 is a liquid crystal, and is filled and sealed in a cylindrical sample support circular bar 13. The upper and lower lids 130 and 230 of the cylindrical sample-supporting circular bar 13 are provided with electrode bars 131 and 231 so as to penetrate the lid and have their tip portions in contact with the liquid crystal 12. Externally exposed portions of the electrode bars 131 and 231 are connected to the voltage variable application device 18. Note that the two electrodes may be formed concentrically with different diameters, and liquid crystal filled between them.

  At the time of measurement, the set voltage is applied between the electrode rods 131 and 231 by the variable voltage application device 18 and the complex dielectric constant at the applied voltage is measured. The measurement method itself of the complex dielectric constant is the same as that of the first embodiment. The voltage characteristic of the complex dielectric constant of the liquid crystal 12 can be obtained by changing the voltage applied by the voltage variable application device 18.

  According to the second embodiment, in addition to the same effect as that of the first embodiment, there is also an effect that the voltage characteristic of the complex dielectric constant of the sample can be obtained.

  The measurement method of the second embodiment can be applied to measurement of a liquid or solid material having voltage dependency similar to that of liquid crystal.

(C) Other Embodiments In the description of each of the above embodiments, the modified embodiment has been referred to. However, modified embodiments as exemplified below can be cited.

  In each of the embodiments described above, the sample support circular rod 13 (in this paragraph, whether or not the sample 12 is present) penetrates through the center of the wide wall of the waveguide 11 so as to be orthogonal. However, if the theoretical value of the S parameter can be calculated, the penetration position is not limited to the center of the wide wall, and the angle is not limited to a right angle. Further, the number of the sample support circular rods 13 to be penetrated is not limited to one. Further, the sample support circular rod 13 may penetrate the two narrower side walls of the waveguide 11.

  In the description of each of the above embodiments, the measurement result output method was not mentioned, but it may be a display output or a print output, and may be a record output to a recording medium or a transfer output to another device. .

  In each of the above embodiments, the measurement of the S parameter of the waveguide 11 in the state where the sample support circular rod 13 is not mounted is also performed each time. However, the set temperature of the same type of waveguide is shown. In the case where the set humidity is the same as the past measurement, the S parameter measured in the past stored in the computer 15 may be used. If the measurement does not include the above-described unknown complex dielectric constant layer, past measurement values may be used in the same manner. For example, the measured value of the past S parameter may be used as the S parameter of the standardized sample support circular rod 13 in which the sample 12 is not provided.

  In the description of each of the embodiments described above, the change of the type of the waveguide and the like has been described by manual operation. However, it may be automatically replaced using a robot or the like. The sample-supporting circular rod 13 may be automatically inserted into or replaced with the waveguide 11 by using a robot or the like.

  In the description of each of the above embodiments, the S parameter of the waveguide 11 to which the sample support circular rod 13 is not mounted is measured first, and then the waveguide to which the sample support circular rod 13 is mounted. Although the measurement of the S parameter of the tube 11 is shown, the measurement order is not limited to this and may be arbitrary.

  In the description of each of the above embodiments, the processing routine of the formula (1) or the formula (2) is common regardless of the specific number of layers of the N + 1 layer. Another processing routine may be prepared separately for each (range). Also, a separate processing routine of formula (1) or formula (2) may be prepared depending on the type of sample, such as for a film or cloth-like sample or a sample to be coated to form a thin film. good.

  In the description of each of the above embodiments, the measurement is performed by sweeping the frequency. However, the measurement may be performed using only one of the frequencies. Any frequency in this case is not limited to a specific frequency such as a resonance frequency of the waveguide. For example, the frequency of the radio wave most radiated to the sample 12 in the usage environment of the sample 12 is applied. Also good.

  In each of the embodiments described above, each concentric layer is described as one component. However, a concentric shape may be achieved by combining components such as halves.

1 is a block diagram showing a schematic overall configuration of a complex dielectric constant measuring apparatus 10 of a first embodiment. It is a perspective view which shows the mounting state of the sample support circular rod with respect to the perforated rectangular waveguide of 1st Embodiment. It is sectional drawing for description of the sample supporting method by the sample support circular rod body of 1st Embodiment. It is a flowchart which shows the measurement procedure of 1st Embodiment. It is a graph which shows an example of the measured value of S parameter of a 1st embodiment. It is a graph which shows the example of a measurement result of the complex dielectric constant and dielectric loss tangent by 1st Embodiment. It is a perspective view which takes out and shows constituent parts, such as a sample in a 2nd embodiment, and a sample support circle stick.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Complex dielectric constant measuring apparatus, 11 ... Perforated rectangular waveguide, 12 ... Sample, 13 ... Sample support circular rod, 14 ... Network analyzer, 15 ... Computer, 16 ... Constant temperature and humidity chamber, 18 ... Variable voltage Application device.

Claims (12)

A circular rod made of a material having an axially symmetric structure of a sample layer having an unknown complex dielectric constant and an N layer having a known complex dielectric constant (which may include an air gap layer);
A waveguide having through holes provided in opposing side walls for penetrating the circular rod of the (N + 1) layer;
Measuring means for measuring a propagation characteristic parameter of the waveguide through which the circular rod is fixed through the through hole;
For the theoretical expression of the propagation characteristic parameter as a function of the unknown complex dielectric constant, which is theoretically determined from the shape of the waveguide and the circular rod and the known complex dielectric constant of the N layer, the measurement And an analyzing means for deriving a complex dielectric constant of an unknown sample layer by applying a measurement result of the means.   A layer having a known complex dielectric constant such that the electromagnetic field energy of the waveguide is concentrated at or near the axis targeted by the axis is disposed outside the sample layer with an unknown complex dielectric constant. The complex dielectric constant measuring apparatus according to claim 1.   The complex dielectric constant measuring apparatus according to claim 2, wherein an innermost layer of the axisymmetric layers is a layer formed of a cylindrical material.   The complex dielectric constant measuring apparatus according to any one of claims 1 to 3, wherein the partial layer of the axial object is formed by winding a constituent material of the layer around an inner layer.   The complex dielectric constant measuring apparatus according to claim 1, wherein an S parameter is used as the propagation characteristic parameter. Opposite circular rods of (N + 1) layers made of a material having an axially symmetric structure between a sample layer of unknown complex permittivity and an N layer of known complex permittivity (which may include an air gap layer) Through and fixed to a waveguide provided with a through hole in the side wall,
Measuring a first propagation characteristic parameter for the waveguide through which the circular rod is fixed,
For the theoretical expression of the propagation characteristic parameter as a function of the unknown complex dielectric constant, which is theoretically determined from the shape of the waveguide and the circular rod and the known complex dielectric constant of the N layer, A method for measuring a complex dielectric constant, comprising: deriving a complex dielectric constant of an unknown sample layer by applying a measurement result of a propagation characteristic parameter.   One layer with a known complex dielectric constant of the circular rod is a side wall of an open container or a sealed container, and a fluid with an unknown complex dielectric constant is not flowed in the open container or the sealed container. The complex dielectric constant measuring method according to claim 6, wherein the sample layer is filled to form a sample layer. The second propagation characteristic parameter for the waveguide to which the circular rod is not fixed, or the N layer in the same state as the (N + 1) layer circular rod except the unknown sample layer Measuring a third propagation characteristic parameter for the waveguide through which the circular rod is fixed,
In the process of deriving the complex dielectric constant of the unknown sample layer, the complex dielectric constant of the unknown sample layer is derived also using the measurement result of the second or third propagation characteristic parameter. The method of measuring a complex dielectric constant according to claim 6 or 7.   A layer having a known complex dielectric constant such that the electromagnetic field energy of the waveguide is concentrated at or near the axis targeted by the axis is disposed outside the sample layer with an unknown complex dielectric constant. The method of measuring a complex dielectric constant according to any one of claims 6 to 8.   The method of measuring a complex dielectric constant according to claim 9, wherein an innermost layer of the axisymmetric layers is a layer formed of a cylindrical material.   The complex dielectric constant measuring method according to any one of claims 6 to 10, wherein the partial layer of the axial object is formed by winding a constituent material of the layer around an inner layer. The complex dielectric constant measurement method according to claim 6, wherein an S parameter is used as the propagation characteristic parameter.

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